Outflowing Helium from a Mature Mini-Neptune [PDF]
The Astrophysical Journal Letters, 2023 We announce the detection of escaping helium from TOI 2134b, a mini-Neptune a few gigayears old. The average in-transit absorption spectrum shows a peak of 0.37% ± 0.05% and an equivalent width of W _avg = 3.3 ± 0.3 mÅ.
Michael Zhang +4 more
doaj +4 more sources
Detection of Atmospheric Escape from Four Young Mini-Neptunes [PDF]
The Astronomical Journal, 2023 We use Keck/NIRSPEC to survey a sample of of young (
Michael Zhang +7 more
doaj +5 more sources
A Mini-Neptune Orbiting the Metal-poor K Dwarf BD+29 2654 [PDF]
The Astronomical Journal, 2023 We report the discovery and Doppler mass measurement of a 7.4 days 2.3 R _⊕ mini-Neptune around a metal-poor K dwarf BD+29 2654 (TOI-2018). Based on a high-resolution Keck/HIRES spectrum, the Gaia parallax, and multiwavelength photometry from the UV to ...
Fei Dai +50 more
doaj +7 more sources
The formation of mini-Neptunes [PDF]
The Astrophysical Journal, 2017 Mini-Neptunes seem to be common planets. In this work we investigate the possible formation histories and predicted occurrence rates of mini-Neptunes assuming the planets form beyond the iceline.
Helled, Ravit, Venturini, Julia
core +5 more sources
Distinguishing Oceans of Water from Magma on Mini-Neptune K2-18b [PDF]
The Astrophysical Journal LettersMildly irradiated mini-Neptunes have densities potentially consistent with them hosting substantial liquid-water oceans (“Hycean” planets). The presence of CO _2 and simultaneous absence of ammonia (NH _3 ) in their atmospheres has been proposed as a ...
Oliver Shorttle +4 more
doaj +7 more sources
Evolutionary Models of Super-Earths and Mini-Neptunes Incorporating Cooling and Mass Loss [PDF]
The Astrophysical Journal, 2015 We construct models of the structural evolution of super-Earth- and mini-Neptune-type exoplanets with hydrogen-helium envelopes, incorporating radiative cooling and XUV-driven mass loss.
Burrows, Adam S., Howe, Alex R.
core +4 more sources
Kepler and the Behemoth: Three Mini-Neptunes in a 40 Million Year Old Association [PDF]
The Astronomical Journal, 2022 Stellar positions and velocities from Gaia are yielding a new view of open cluster dispersal. Here we present an analysis of a group of stars spanning Cepheus ( l = 100°) to Hercules ( l = 40°), hereafter the Cep-Her complex.
L. G. Bouma +10 more
doaj +4 more sources
JWST Observations of K2-18b Can Be Explained by a Gas-rich Mini-Neptune with No Habitable Surface [PDF]
The Astrophysical Journal LettersThe James Webb Space Telescope (JWST) recently measured the transmission spectrum of K2-18b, a habitable-zone sub-Neptune exoplanet, detecting CH _4 and CO _2 in its atmosphere.
Nicholas F. Wogan +5 more
doaj +4 more sources
Occurrence and core-envelope structure of 1-4× Earth-size planets around Sun-like stars. [PDF]
Proc Natl Acad Sci U S A, 2014 Small planets, 1-4x the size of Earth, are extremely common around Sun-like stars, and surprisingly so, as they are missing in our solar system. Recent detections have yielded enough information about this class of exoplanets to begin characterizing ...
Marcy GW +5 more
europepmc +4 more sources
Habitable Evaporated Cores: Transforming Mini-Neptunes into Super-Earths in the Habitable Zones of M Dwarfs [PDF]
, 2015 We show that photoevaporation of small gaseous exoplanets ("mini-Neptunes") in the habitable zones of M dwarfs can remove several Earth masses of hydrogen and helium from these planets and transform them into potentially habitable worlds. We couple X-ray/
Barnes, Rory +5 more
core +2 more sources